Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261199AbVDUDId (ORCPT ); Wed, 20 Apr 2005 23:08:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261200AbVDUDId (ORCPT ); Wed, 20 Apr 2005 23:08:33 -0400 Received: from ms-smtp-05.texas.rr.com ([24.93.47.44]:25275 "EHLO ms-smtp-05-eri0.texas.rr.com") by vger.kernel.org with ESMTP id S261199AbVDUDIa (ORCPT ); Wed, 20 Apr 2005 23:08:30 -0400 Message-ID: <42671901.4000805@ammasso.com> Date: Wed, 20 Apr 2005 22:07:45 -0500 From: Timur Tabi User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.6) Gecko/20050319 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Troy Benjegerdes CC: Bernhard Fischer , Arjan van de Ven , linux-kernel@vger.kernel.org, openib-general@openib.org Subject: Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation References: <200544159.Ahk9l0puXy39U6u6@topspin.com> <20050411142213.GC26127@kalmia.hozed.org> <52mzs51g5g.fsf@topspin.com> <4263DBBF.9040801@ammasso.com> <1113840973.6274.84.camel@laptopd505.fenrus.org> <4263DF70.2060702@ammasso.com> <1113853240.6274.99.camel@laptopd505.fenrus.org> <20050418200711.GI15688@aon.at> <20050421021713.GP999@kalmia.hozed.org> In-Reply-To: <20050421021713.GP999@kalmia.hozed.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1375 Lines: 24 Troy Benjegerdes wrote: > Someone (aka Tospin, infinicon, and Amasso) should probably post a patch > adding '#define VM_REGISTERD 0x01000000', and some extensions to > something like 'madvise' to set pages to be registered. > > My preference is said patch will also allow a way for the kernel to > reclaim registered memory from an application under memory pressure. I don't know if VM_REGISTERED is a good idea or not, but it should be absolutely impossible for the kernel to reclaim "registered" (aka pinned) memory, no matter what. For RDMA services (such as Infiniband, iWARP, etc), it's normal for non-root processes to pin hundreds of megabytes of memory, and that memory better be locked to those physical pages until the application deregisters them. If kernel really thinks it needs to unpin those pages, then at the very least it should kill the process, and the syslog better have a very clear message indicating why. That way, the application doesn't continue thinking that everything's still going to work. If those pages become unpinned, the applications are going to experience serious data corruption. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/